Grinding wheel



Dec. 13, 1966 F. w. LI NDBLAD 3,290,334

GRINDING WHEEL Filed July 15, 1964 &\\\ /////////////Au INVENTORFREDERICK W. LiNOBLAD United States Patent 3,290,834 GRKNDING WHEELFrederick W. Lindblad, 835 Illinois Ava, Aurora, llill. Filed July 15,1964, Ser. No. 382,831 15 @laims. (Ci. 51--2il6) This invention relatesgenerally to grinding wheels, and more particularly to a grinding wheelof the type in which the abrasive member that performs the grindingoperation is secured to a body or core.

In grinding wheels of the foregoing type, there is a considerable amountof heat produced by the grinding operation with the result that both theabrasive member and core become heated. Furthermore, in many instancesthe abrasive member and core do not adequately dissipate the heat to thesurrounding atmosphere. Expansion, caused by heat, tends to loosen thehold of the bonding agent on the individual diamond particles, therebyincreasing the loss of diamond particles. It also tends to weaken thebond between the core and the abrasive memher or abrasive wheel section,especially if the core or the adhesive used to secure the abrasivemember section to the core is a plastic, such as a synthetic resin.

It is an object of the present invention to provide a grinding wheel inwhich a substantial amount of heat produced during the grindingoperation is dissipated from the wheel so as to prevent overheating andthe above mentioned weakening resulting from the overheating.

It is a further object of the present invention to provide a grindingwheel of the type stated which eliminates to a substantial extent theneed for dressing the grinding wheel as the abrasive member wears duringthe useful life of the wheel.

In accordance with the objects of the present invention, the body has aseat which supports the abrasive member, the seat being of a materialhaving a high thermal conductivity as compared to that of the abrasivemember and the part of the body adjacent to the seat. The seat is ofsuch size and shape as to present a substantial area to the atmosphereso that the seat conducts heat from the region of the grinding ring andin turn transmits heat to the atmosphere, thereby reducing thetemperature build-up on the body. The abrasive member may be of a typehaving diamond abrasive particles and the body may be of a syntheticresin. The seat may be of copper or of aluminum, or may be a mixture ofa major proportion of powdered copper or aluminum or even silver, and aminor proportion of a plastic binder.

The attainment of the above and further objects of the present inventionwill be apparent from the following specification taken in conjunctionwith the accompanying drawing forming a part thereof;

In the drawing:

FIG. 1 is a front elevational view of a grinding wheel constructed inaccordance with and embodying the present invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view similar to FIG. 2 and showing amodified form of the present invention;

FIG. 4 is a sectional view through the axis of rotation of another formof grinding wheel embodying the present invention; and

FIG. 5 is a sectional view through the axis of rotation of still anotherform of grinding wheel that embodies the present invention.

Reference may now be had to the drawing, which illustrates a preferredembodiment of the present invention, and wherein like referencecharacters designate like parts throughout.

3,29%834 Patented Dec. 13, 1966 The grinding wheel 1 comprises a core orbody 3 which may be a flared cup-shaped member molded or otherwisefabricated of any suitable material. For example, the body 3 may beformed of nylon or of a phenolic resin of the type disclosed in my US.Patent 2,703,437. The body 3 may have any suitable shape such as thefrustoconical shape shown with the frusto-c'onical side wall 5terminating at its smaller diameter end in a body end wall '7, thelatter lying at right angles to the central longitudinal axis 9 of thebody and having a hole 11 centered on the axis for mounting the body 3upon the arbor of a grinding machine.

At its larger diameter end, the side wall 5 has an outwardly flaringfrusto-conical seat 13 the outer frustoconical surface of which receivesand supports a frustoconical grinding ring 15. The seat 13 is of amaterial having a high thermal conductivity as compared to that of thegrinding ring 15 and the body 3. For example, the seat 13 may comprise amixture of in the order of powdered copper or aluminum and 10% syntheticresin binder. The resin binder may be similar to the composition of thebody 3. The grinding ring 15 abuts a shoulder 17 that is formed on thebody wall 5 and lies substantially at right angles to the axis 9. Theseat 13 supports the grinding ring 15 substantially up to its largerdiameter end. The seat 13 is, therefore, in effect a reduced thicknesscontinuation of the side wall 5 and the inner surface 19 of the seat 13is exposed to the interior of the body 3.

The grinding ring 15 may be of any conventional type. One such type maybe a ring having industrial diamond abrasive particles molded within abody of plastic. The grinding ring 15, seat 13, and body 3, may bemolded or otherwise assembled together in any suitable manner so thatthe grinding ring 15 is bonded to the seat 13 and the shoulder 17.

When the griding wheel 1 is in use, heat is generated at the grindingsurface 16 of the grinding ring 15. The grinding ring 15 and resin body3 are relatively poor heat conductors as compared to the essentiallymetallic seat 13. However, the grinding ring 15 by the seat 13 and heatis radiated and conducted to atmosphere from the seat 13 from the innersurface 19 thereof. This reduces excessive temperature rise at theshoulder 17 and the bonded interface of the seat 13 and grinding ring 15which might cause the resin of the body or the bonded interface of theseat 13 and grinding ring 15 to become charred 0r softened and therebyweaken the bond between the grinding member or ring and its supportingbody. It also reduces the thermally caused expansion of the plastic orother material that has its locking hold on the individual diamondparticles, thereby reducing loss of the individual particles from theabrasive ring member.

Vanes 21 may be integrally formed on the interior of the body 3 as atthe juncture of the side and end walls, 5, 7. These vanes 21 arepreferably circumferentially spaced about the axis 9 and may extendalong the wall 5 up to the seat 13. The vanes 21 act as fan blades andmaintain a flow of air across the inner surface 19 of the seat 13 tofacilitate transfer of heat from the seat 13 to the atmosphere.

The powdered metal-resin mixture is sufiiciently soft so that iteliminates to a significant extent the need for dressing the wheel asthe grinding surface 16 of the ring 15 progressively wears.

The seat 13 may also have incorporated therein a sec ondary abrasivesuch as silicon carbide or alumina. A secondary abrasive of this type ishelpful in grinding steel since the secondary abrasive helps prevent thesteel from smearing on the diamond, which it does not do on thesecondary abrasive.

heat is conducted away from A modified form of grinding wheel is shownin FIG. 3. In the grinding wheel of FIG. 3, the seat 13a is of a solidmetal ring, such as copper or aluminum, and has circumferentially spacedfingers 23 which are imbedded in the plastic of the body to lock theseat 13a in place onto the body. Other suitable means may be used forsecuring the seat 13a to the body 3.

In the grinding wheel shown in FIGS. 4 and 5, the supporting bodies mayeach be in the form of a cylindrical disc 25 of plastic or othersuitable material. Each disc has a hole 27 centered on the longitudinalaxis 9b of the disc for mounting the disc on a grinding machine arbor.

In FIG. 4, the cylindrical seat 13b is a ring bonded to one side face 28of the disc 25 at the periphery thereof, and a cylindrical grinding ring15b is bonded to the axially presented face 30 of the seat 13b. Thebonds between the grinding ring 15b, seat 13b, and disc 25 may beeffected in any suitable manner. Epoxy resin adhesives have been foundsuitable for this purpose.

The seat 1311 may be of a composition similar to that of the seats 13and 13a previously described and have a substantial thickness. It may bemany times greater than the thickness of the grinding ring 15b. In anyevent, the thickness of the seat 13b is such as to provide radiallyinner and outer surfaces 29, 31 that present a substantial area to theatmosphere so that heat from the grinding (ring 15b will be dissipatedand will not be destructive to the plastic disc or the bonds between theparts of the grinding wheel.

The grinding wheel of FIG. is similar to that shown in FIG. 4 exceptthat the seat 130 is a ring that is bonded to the outer cylindricalsurface 32 of the disc 25, and the grinding ring 15c, is, in turn,bonded to the outer cylindrical surface 34 of the seat 130. The seat 130is of sufficient radial thickness to provide annular side surfaces 33,35 on the seat 130 from which heat is dissipated to the atmosphere fromthe grinding ring 15c.

The diamond particles used in the grinding wheels are so hard that theyare exceedingly resistant to wearing forces, even the extreme wearingforces of grinding cemented carbides, oxides, and ceramics. The wear onthe diamond wheel is caused primarily by other than wear on the diamondparticles. Heat is generated in the grinding process. This weakens thelocking action which holds the individual diamond particles in place.When this happens, the grinding forces are sufficient to pull thepartially used diamond particles from the bond. Proof of this can beseen in the fact that when the diamond is reclaimed from the grindingswarf, an appreciable percentage of it is of the same size as it waswhen it Went into the diamond wheel.

For the above reason, it is important to provide a maximum 'rate of heatdissipation. Most diamond cup grinding wheels are made of a blackmineral filled plastic core of material which is an excellent heatinsulator. This retards escape of heat produced in the diamond section,with a resulting temperature increase in the diamond section. It hasbeen this temperature increase that is responsible for excessive diamondwheel wear, as pointed out above.

When a cast or pressed metal aluminum core is used, the coefficient ofthe expansion of the aluminum is so great that it is diificult to holdthe size of the core due to thermal expansion unless means is providedto facilitate heat dissipation. Copper, on the other hand, has almosttwice the heat conductivity as aluminum and about onehalf the linearcoefficient of expansion. Copper would be too heavy to use in the wholewheel core, but the annula r copper ring as used in the structure abovedescribed need not add any significant weight to the wheel. The smallamount of added weight in the periphery of the wheel does, however,serve as a fly wheel effect for smoother grinding without adding deadweight to the Whole wheel, which adversely affects the bearings ofgrinding machines. The annular copper ring in the diamond Wheel Core ofthe present invention backs up the diamond section, thereby absorbinggrinding heat and conducting it readily into the areas of thesurrounding moving, cooling air, thereby eliminating, or substantiallyreducing, the harmful effects that come from excess heat.

In compliance with the requirements of the patent statutes I have hereinshown and described a preferred embodiment of the invention. It is,however, to be understood that the invention is not limited to theprecise construction herein shown, the same being merely illustrative ofthe principles of the invention. What is considered new and sought to besecured by Letters Patent is:

1. A grinding wheel comprising a body having means for mounting the samefor rotation about the longitudinal axis of the body, said body having aseat that surrounds said axis, a grinding ring bonded to said seat, saidseat supporting the grinding ring over at least a portion of the axiallength thereof, said seat being of a material having a high thermalconductivity as compared to that of the grinding ring and the part ofthe body adjacent to the seat, said seat being of such axial length andshape as to present a substantial area to the atmosphere so that theseat conducts heat from the grinding ring and transmits heat to theatmosphere.

2. A grinding wheel according to claim 1 in which said material includesa metal of the group consisting of copper and aluminum.

3. A grinding wheel according to claim 1 in which said material is ahomogeneous mass that includes a major proportion of powdered metal anda minor proportion of a plastic bonding agent.

4. A grinding wheel according to claim 3 in which the grinding ring is adiamond matrix and the seat includes abrasive particles having ahardness less than that of the diamond abrasive.

5. A grinding wheel according to claim 1 further including means forimparting a flow of coolant over the seat as the wheel rotates.

6. A grinding wheel comprising a body having means for mounting the samefor rotation about the longitudinal axis of the body, a seat secured tothe body and being centered on said axis, and a grinding ring secured tothe sea-t, said seat being of a material having a high thermalconductivity as compared to that of the grinding ring and the part ofthe body adjacent to the seat, said seat between the grinding ring andbody being relatively thick as compared to the thickness of the grindingring to provide sufficient surface area presented to the atmosphere todissipate a substantial amount of heat from the grinding ring andthereby prevent an excessive increase in temperature of the grindingring.

7. A grinding wheel comprising a hollow frusto-conical body having meansat the smaller diameter end for mounting the same for rotation about thelongitudinal axis of the body, the larger diameter end (if the bodyhaving a frusto-conical ring that constitutes a seat for a grindingring, an annular shoulder formed on the outer surface of the bodyadjacent to the smaller diameter end of the seat and facing in thedirection toward said larger diameter end of the body, and a hollowfrusto-conical grinding ring having an inner surface on the seat and itssmaller diameter end abutting said shoulder and with the seat supportingthe grinding ring over a major portion of its axial length, said seatbeing of a material having a high thermal conductivity as compared tothat of the grinding ring.

8. A grinding wheel according to claim 7 in which the grinding ring is adiamond matrix, the body is plastic, and the seat is primarily a metalof the group consisting of copper and aluminum.

9. A grinding wheel according to claim 7 in which the material of theseat is powdered metal in a plastic matrix.

10. A grinding ring according to claim 7 in which the body is plasticand the seat is a preformed piece of metal having means embedded in thebody.

11. A grinding wheel according to claim 7 in which the body has coolingvanes for imparting a flow of cooling air over the seat as the wheelrotates.

12. A grinding ring according to claim 9 in which the material of theseat also includes an abrasive that is softer than the diamond abrasive.

13. A grinding wheel comprising a hollow body having a frusto-conicalwall, a frusto-conical grinding ring located on the surface of the wallat the larger diameter end thereof and supported by the wall over amajor portion of the axial length of the grinding ring, the part of thewall that supports the grinding ring comprising as a major portionthereof metal having a high thermal conductivity as compared to theportion of the body adjacent to said part and the grinding ring, andcooling vanes on the body for maintaining a flow of cooling fluid oversaid part of the wall.

14. A grinding wheel comprising a hollow frusto-conical supporting bodyhaving means at its smaller diameter end for mounting the same forrotation about the central longitudinal axis of the body, said bodyhaving adjacent to its larger diameter end an annular shoulder formed onits outer surface and extending toward said axis, and a hollowfrusto-conical grinding ring the smaller diameter end of which abuts theshoulder with said ring flaring radially outwardly from said shouldertoward its larger diameter end, said ring being backed at its innerfrustoconical surface by a frusto-conical seat on the supporting bodythat extends from said shoulder to the larger diameter end of the body,said ring terminating at its larger diameter end in a grinding surface,the ring being of substantially smaller mass than the mass of thesupporting body, said seat being a mixture of a minor proportion ofplastic and a major proportion of metal to dissipate heat from theinterfaces of the grinding ring and the shoulder and which may beprogressively dressed away as the grinding surface is progressively wornwhereby the edge of the seat at the larger diameter end of the body maybe maintained in reinforcing position immediately adjacent to saidgrinding surface during progressive wearing away of the ring.

15. A grinding wheel according to claim 14 further including coolingvanes for imparting a flow of coolant over the inner frusto-conicalsurface of the seat to facilitate the. dissipation of heat therefrom.

References Cited by the Examiner UNITED STATES PATENTS 2,137,201 11/1938Boyer 51-209 3,161,995 12/1964 Lindblad 51--209 ROBERT C. RIORDON,Primary Examiner.

L. S. SELMAN, Assistant Examiner.

6. A GRINDING WHEEL COMPRISING A BODY HAVING MEANS FOR MOUNTING THE SAMEFOR ROTATION ABOUT THE LONGITUDINAL AXIS OF THE BODY, A SEAT SECURED TOTHE BODY AND BEING CENTERED ON SAID AXIS, AND A GRINDING RING SECURED TOTHE SEAT, SAID SEAT BEING OF A MATERIAL HAVING A HIGH THERMALCONDUCTIVITY AS COMPARED TO THAT OF THE GRINDING RING AND THE PART OFTHE BODY ADJACENT TO THE SEAT, SAID SEAT BETWEEN THE GRINDING RING ANDBODY BEING RELATIVELY THICK AS COMPARED TO THE THICKNESS OF THE GRINDINGRING TO PROVIDE SUFFICIENT SURFACE AREA PRESENTED TO THE ATMOSPHERE TODISSIPATE A SUBSTANTIAL AMOUNT OF HEAT FROM THE GRINDING RING ANDTHEREBY PREVENT AN EXCESSIVE INCREASE IN TEMPERATURE OF THE GRINDINGRING.